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Mr. Jason Gaitan July 13, 2020 at the active industrial rail yard Site. The C/I ESLs for TPH-DRO and TPH-MO are 1,200 milligrams per kilogram (mg/kg) and 180,000 mg/kg, respectively (SF-RWQCB 2019). Data Validation Pace laboratory analytical reports were validated by GHD Inc. (GHD) in a memoranda dated July 9, 2020. Based on the GHD assessment in the data validation memorandum, the data associated with this project is acceptable without qualification. Samples were prepared and analyzed within the required holding times. Analytical results and data validation are included in Attachment 2. Soil Analytical Chromatogram Review Laboratory chromatograms for the TPH-DRO data were compared against the TPH-DRO standard chromatograms to assess the type of petroleum hydrocarbon present and the degree of weathering for the TPH-DRO concentrations in the soil samples. The purpose of the chromatogram review was to identify the soil samples with non-weathered diesel detections to be removed during the excavation proposed in this Work Plan. Signatures of non-weathered diesel to severely weathered diesel and oil mixtures, or natural organic matter were observed in the chromatograms. Non-weathered diesel was noted in samples SS-1-16, SS- 1-22, SS-1-48, SS-4-12, SS-4-40, SS-5-14, SS-6-14, SS-7-17, and SS-7-60. Diesel appeared slightly more weathered in lighter-range hydrocarbons compared to the shallower samples in samples SS-1-48, SS-4-40, and SS-7-60. This is likely due to evaporation during migration from shallower sediments. Severely weathered diesel was present in samples SS-2-16, SS-3-14, SS-5-49, and SS-6-46. TPH-DRO was not detected above the laboratory reporting limit(RL) in samples SS-2-54, SS-3-14, SS-5-49, SS-8- 9, SS-8-24, SS-9-22, and SS-9-33. Copies of the chromatograms are included in Attachment 2. Soil Analytical Results and Evaluation TPH-DRO concentrations in soil samples ranged from not detected above the RL to 9,100 milligrams per kilogram (mg/kg; SS-1-22). TPH-DRO concentrations exceeded the 1,200 mg/kg C/I ESL in six shallow soil samples SS-1-16, SS-1-22, SS-4-12, SS-5-14, SS-6-14, and SS-7-17.Analytical results indicate that TPH-DRO is generally delineated laterally in soil borings to the east by SS-2 and SS-3, to the southwest by SS-8, and to the northwest by SS-9. TPH-DRO is delineated vertically at each sample location. TPH-MO concentrations in soil samples ranged from not detected above the RL to 1,060 mg/kg (SS-5- 14). TPH-MO concentrations did not exceed the 180,000 mg/kg C/I ESL. Soil analytical results are presented in Table 1 and on Figure 3. Laboratory analytical reports, chromatograms, and chain-of-custody documentation are included in Attachment 2. PROPOSED SCOPE OF WORK An additional excavation is proposed to remove remaining diesel-impacted soil above the C/I ESL associated to the November 10, 2019 release area. The proposed excavation area is shown on Figure 3 and generally delineated by areas of severely weathered diesel and where TPH-DRO concentrations in soil samples were below the C/I ESL. arcadis.com Page: 2020.07.13_Soil Sample Summary and Excavation Work Plan.docx 3/5